A full restructure

pkg/crypto/md5c/md5c.go

@@ -0,0 +1,48 @@
+// !build linux,amd64
+
+package md5c
+
+// #include "md5.h"
+import "C"
+import (
+	"io"
+	"unsafe"
+)
+
+func context() *C.MD5_CTX {
+	var ctx C.MD5_CTX
+	C.MD5_Init(&ctx)
+	return &ctx
+}
+
+func write(buffer []byte, ctx *C.MD5_CTX) {
+	size := len(buffer)
+	data := unsafe.Pointer(&buffer[0])
+	C.MD5_Update(ctx, data, C.ulong(size))
+}
+
+func Sum(reader io.Reader) ([]byte, error) {
+	ctx := context()
+	var err error
+	var length int
+	for err == nil {
+		byteBuffer := make([]byte, 1024*1024)
+		length, err = reader.Read(byteBuffer)
+		// break here since byteBuffer will go out of range
+		// when invoking subsequent write() call
+		if length == 0 {
+			break
+		}
+		byteBuffer = byteBuffer[0:length]
+		write(byteBuffer, ctx)
+	}
+
+	if err != io.EOF {
+		return nil, err
+	}
+
+	outputBuffer := make([]byte, 16)
+	coutputbuff := (*C.uchar)(unsafe.Pointer(&outputBuffer[0]))
+	C.MD5_Final(coutputbuff, ctx)
+	return outputBuffer, nil
+}